Grinding machine and footstock thereof



Dec; 14, 1948.

E. BUGATTI GRINDING MACHINE AND FOOTS'IOCK THEREOF 2 Sheets-Sheet 1 Filed 001',- 29, 1945 a w a j 2 1 H x 7 8 v n i-m 0 'flldI/l/l/l/l/III/ Dec. 14, 1948. E. BUGATTI 2,456,252

GRINDING MACHINE AND FOOTSTOCK THEREOF Filed Oct. 29, 1945 2 Sheets-Sheet 2 ,4 a i? I v lli lmil pm Inn.

Patented Dec. 14-, 1948 STATES PTENT GRINDING MACHINE AND FOOTSTOCK THEREOF Ettore Bugatti, Paris, France Section 1, Public Law 690, August 8, 1946 Patent expires January 14, 1964 5 Claims. 1

Grinding between stocks is one of the commonest methods used for machining cylindrical or conical works with accuracy. The work is held between the conical centres of the headstock (which carries the work round in its rotation) and the footstock (adapted to be moved longitudinally on the table as required for the work).

It is an object oi my invention to provide an improvement whereby works of very small diameter may be ground between stocks, the production of such slight diameters being secured with maximum accuracy by passing the grinding wheel on a diamond provided on the iootstock.

According to this invention, a grinding machine footstock including its conical centre is partly or wholly located on the side away from the grinding wheel of a vertical plane containing the innermost generatrix of said grinding wheel when the latter is in the position nearest to the work centre. This position is determined by the minimum diameter of the works to be ground. In the present instance, this diameter may amount to about 5 millimeters. I

The diamond or if need be the diamonds ma be located either above or below the axis of the work, thus above or below the axis of the grinding wheel, as near as possible to said axis and in such a position that the grinding wheel can contact said diamond or diamonds before each grinding stroke. The foregoing arrangement may be applied indiscriminately to any one of both types of machines for grinding between stocks, to wit those in which the grinding wheel is moved along the work, and those in which the work travels in front of the grinding wheel.

The diamond or diamonds are preferably mounted in a position adjustable transversely according to the desired diameter for the finished work, taking into account the correction to be made as the diamond or diamonds are not rigorously at the level of the grinding wheel axis.

The carriage which supports the footstock centre and allows it of travelling lengthwise as required by the work is preferably shaped as a prism having a trapezoidal section, the parallel bases of which are disposed vertically on the side already referred to of the vertical plane tangent to the grinding wheel surface.

The support for said carriage, which forms the footstock body, may rest on the bed of the machine and, being suitably guided, may be moved lengthwise when the carriage stroke is not large enough.

The diamond or diamonds are preferably set in cylindrical or prismatic tools which are movable 2 transversely in guides provided in the iootstock body, in order that the point of said diamond or diamonds may be brought to the proper position for the securing the required diameter.

The advantages of the foregoing arrangement are as follows:

1. It is possible to grind works having small diameters between stock centres while with known machines, precautions must be taken in order that the grinding wheel does not travel beyond the end of the work so as not to contact any portion of the footstock. In view of this requirement, one generally did not grind certain works between stocks; the works must then be mounted on the headstock in overhanging posi' tion, and this is a jeopardizing practice in such a case.

2. A work or a series of identical works may be ground to a predetermined diameter which is secured once for all by adjusting the position of the diamond or diamonds in transverse direction and causing the grinding wheel to pass on it or them either before grinding each work or, where it is necessary to operate in a plurality of steps, before each cut.

3. A work having a complex outline or profile may be ground with several grinding wheels of different diameters. To this end, the grinding wheels are caused to contact diamonds, one for each grinding wheel, the diamond tools being disposed transversely, so as to secure the desired diameters on the work. The position of the carriage supporting the grinding wheel spindle being "marked by means of a Vernier provided for this purpose, the carriage is then moved backwards so as to clear the diamond-tools or the work (according to their relative position) in the lengthwise movement, then it is moved towards the work to the extent required from the reading on the Vernier.

The following description with reference to the drawings given solely by way of examples will show how this invention may be carried out.

Fig. 1 is a cross-section (along line I+I on Fig. 3) of a iootstock constructed in accordance with my invention.

Fig. 2 shows in cross-section (along line 1I-II on Fig. 3) a detail of said footstock.

Fig. 3 is an elevation of the footstock with parts broken away. 7

Fig. 4 is a longitudinal section taken along line IV-IV on Fig. 3.

Figs. 5 and 6 illustrate an alternative arrangement with several diamond-tools.

Grinding wheel I is shown in part on Fig. 1.

Its centre is in the same horizontal plane as the axis of centre 2 which is set in a carriage 3. Carriage 3 is slidably mounted in a support 4 which is itself movable on a table 5, a shoulder 6 of which guides support 4 in cooperation with a strip 7.

Strip 1 is secured to table 5 by a series of screws 8, with an interposed liner 9 for adjustin the amount of play in the slideway 6, 5, I. Alternatively support 4 may be guided by any other known means (dovetail, V, feathers and the like).

Support 4 can be kept immovable on table .5 by one or more square-headed bolts I provided with nuts II and washers I2, according to awe'llknown arrangement.

Secured on carriage 3 by screws JLis astrip I3 provided to protect the lower slideway 'insupport 4 against ingress of water and dust or filings from the grinding wheel.

Diamond i is set in a tool IB which is preferzablgylof -irusto-conical shape (-morse'or .like cone 18,5 illSfid for removable members of machine-tools such as drills, lathe or grinding machine stock centres. etc). Tool d6 is-clamped-in'thezconical :bore 12? of :a holder I8 in which a recess "IE9 is provided to enable of pushing tool zifiiout :of the ibore. .Holder 1!:8 :which has a :preferabl-y square :or rectangular cross-section :is .accomodated in :a part integral *with {carriage .3 'and having a (bore -21. One or several set screws 22 in part 2.0 .01 any other known means secure the position-o'f holder I18.

:FIhe amount by which diamond I15 projects beyond ithe "vertical plane including the axis of stock centre? is determined .as a function of l. The :diameter ofrthe work :to be produced;

2. The distance from diamond I5 to the hori- 2201113221 plans including the .axis "of stock centre 2 '3. The diameter .of the grinding wheel.

The last factor has but little influence on the result as the radius mfthegrinding wheel :is relativelygreat with respectto .the vertical distance referred to under 22. Said vertical distance may :be as :low as -a -few ;millimeters, :and :in actual practice the second and third :tactors :may be neglected, chiefly if the diameter of the first {ground worksischecked. .Likesupportd, carriage .53 should be held immovable in operative position, in certain cases. For this purpose, a wedge 2.3

(FigsMZand'S) is'guided in a slideway 24 provided .:in the upper part 25 which provides a guide for carriage :3 in support'fl. Alspindle 26 pinned at :21 on hand lever :28 :in which it :is screwed, strongly presses wedge .23 on the corresponding .iace of :carriage :3. wedge "23 i-having a screwthreaded here to accommodate the screwthreadedendoflspindle 26.

Carriage .3 (Figs. Band 4) is smoved in support 43 by a screw 30 and a nut -3I fast with carriage 3 to which it is secured by screws 32. Attached [to support 4 by screws T34 is a lid (or -cover 33 *whichholds screws .30 through;its hub portion 33 bis. Screw .38 has cylindrical extensions 30 his and :30 ten thejformer being :borne in hub 33'ibis while thedattertilter is fitted withca hand-wheel 35. keyed by a feather 36 and locked by a nut -3'I.

4 illustrates the general shape .:of a footstock in accordance with :this invention. The cylinder generated by the grinding wheel inits axial movement is shown by its projection '38 which isdelimitedbythe projection of a cylindrical work 39 being machined. Stock centre .2 .setincarriage -3 is ,cut-awayalong a plane parallel with its axis so :as :to :leave clearance between the .fiat face ,of :said centre and projection :38.

Diamond I5 and holder I8 are shown in chain and dot lines, the point of diamond I5 lying in the area swept by the grinding wheel (said area being delimited by projection 38).

The exposed portioniof lcarriage 3 may be concealedbya metal sheet illl fast withsupport 4.

Resilient means such as springs may be interposed between nut (ii and carriage 3 in order that the work be not abruptly squeezed between the stock centres. Such means are well known in conventional technics of grinding machines.

.Eigs. .5 and 6 illustrate an arrangement with several diamond tools on carriage 3; grinding wheels I, 'I bisand I ter have stepped diameters to ena'ble-of grinding works with complex outline. .The use -0f such an arrangement requires that grinding .wheels I, I bis, I ter are withdrawn backwards after operation of diamonds I5, I5 bis, I5 ter. The return of the wheels to operative position (in contact with the work) is obtained with accuracy with the help of avernier on the carriage :for the grinding wheel spindle, by using the mark observed when truing-up the wheels :withthe diamonds.

What I claim is:

1. In a grinding-machine footstock, the combination "of a carriage having :a substantially planar outer face and a recess extending from :sai-diaces substantially at :right angles thereto; a=diamond holder-slidablyhe'ld in said :recess for adjustment purposes; means on the carriage for :cl-ampingsai'd diamondholder in said recess; and a footstock :centre :having a :pointed end, set in said carriage .in .close proximity .to said :recess,

' :with the pointed :end axis considerably :nearer to said outer face than :to the inner face of :said carriage.

2. In a grinding machine having a bed'and a grinding wheelfithe combination of a longitudinal support slidably mounted on said bed, including a fiat upstanding member which has a generally concave wall on the side facing said grindingwheel, said member having a longitudinal slot in said wall; a longitudinal carriage slidably Iheld said slot, having its outer surface flush with said wall and'a recess extending 'from said surrface:substantially at right angles thereto; a diamond tool :adjustably clamped .in said recess; a footstockcentre having a pointed end, set in said carriage in close :proximity :to said recess, with the pointed end axis considerably nearer to said :outer face thanito the inner'face of said carriage; :and means interposed between said support and :said carriage :for moving the latter in said slot.

3. In a grinding machine 'footstock, the com bination of a carriage having a substantially planar outer face and a plurality of parallel :recesses extending from said vface substantially at :right angles thereto; a diamond holder slidably held ineach of said recesses for adjustment purposes; means on the carriage for separately clamping each-diamondho'lder in the corresponding recess, and a iootstock centre having a pointed rend, setin said carriage inclose proximity to said L'IECESS, with the pointed end axis considerably nearer to said outer face than to the inner face of said carriage.

4. A grinding-machine 'footstock which com- :prisesarigid body-having side walls, one of which is;s.ubstantially planar in its upper part; a foot- :stock centre supported in said body with its axis considerably nearer to said substantially planar upper part of said side wall than to the opposite :side wall; a diamond located outside said body :in eclose :proximity to said substantially planar upper part of said side wall, at a level very close to the level of said rootstock centre axis; and means for supporting said diamond from said footstock body.

5. In a grinding-machine rootstock, the combination of a support having a substantially planar, vertical wall and a longitudinal keyway on the side of said wall; a key-shaped carriage operatively engaging said keyway with its expcsed face co-planar with said wall, having a longitudinal recess in said exposed face running to an end of said support, said carriage further having a cross recess in its exposed face, substantially at right angles thereto in close proximity to said longitudinal recess; a rigid elongated member in said longitudinal recess, having an exposed planar face flush with said exposed face of the carriage and an integral pointed tip projecting from said end of the carriage, said tip having its axis located considerably nearer to said exposed planar face of said rigid member than to the opposite wall thereof; and a diamond tool held in said cross recess with its operative end slightly protruding out of said cross recess.

ETTORE BUGATTI.

REFERENCES CITED The following references are of record in the file of this patent:

Bath May 3, 1938 

